When calcium metal is dropped in water, it begins to bubble vigorously and react with the water, producing hydrogen gas and a cloudy white precipitate of calcium hydroxide.
$
\underset{\substack{\text { Calcium } \\ \text { metal }}}{\mathrm{Ca}}+2 \mathrm{H}_2 \mathrm{O} \longrightarrow \underset{\substack{\text { Calcium } \\ \text { hydroxide }}}{\mathrm{Ca}(\mathrm{OH})_2}+\underset{\substack{\text { Hydrogen } \\ \text { gas }}}{\mathrm{H}_2}
$
The reaction of $\mathrm{CaH}_2$ with water can be represented by
$\underset{\substack{\text { Calcium } \\ \text { hydride }}}{\mathrm{CaH}_2}+2 \mathrm{H}_2 \mathrm{O} \longrightarrow \underset{\substack{\text { Calcium } \\ \text { hydroxide }}}{\mathrm{Ca}(\mathrm{OH})_2}+\underset{\substack{\text { Hydrogen } \\ \text { gas }}}{2 \mathrm{H}_2}$
The two hydrolysis products, $\mathrm{H}_2$ and $\mathrm{Ca}(\mathrm{OH})_2$ can be readily separated from the dried solvent